Self-propelled, single-stage snow thrower

ABSTRACT

A snow thrower having a frame, an engine attached to the frame and having a horizontal output shaft, the output shaft having a first axis of rotation, a first rotary member rotatably fixed to the engine output shaft, and a rotating auger connected to the frame, the auger having a second axis of rotation. A second rotary member is rotatably fixed to the auger, the first and second rotary members forming a first pair of rotary members and being in selective operative engagement with each other, whereby the auger is selectively driven by the engine. An axle is connected to the frame and has a third axis of rotation, the first, second and third axes of rotation being substantially parallel. A third rotary member in is operative engagement with the axle, and a pair of ground-engaging wheels is attached to the axle. A fourth rotary member is rotatably fixed to either the auger or the engine output shaft, the third and fourth rotary members forming a second pair of rotary members and being in operative engagement with each other, whereby the axle is driven by the fourth rotary member. A belt is also included, at least one of the first and second pairs of rotary members being in operative engagement through the belt.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to snow throwers, and particularly to single-stage snow throwers.

[0002] Single-stage snow throwers are well known in the art, and provide a relatively inexpensive alternative to dual-stage snow throwers. Typically, single-stage snow throwers provide a high-speed rotating auger provided with friction material on its blade edges, and the snow thrower is propelled forward by bringing the auger blade edges into engagement with the ground. To bring the auger into engagement with the snow-covered surface, the operator must lift upward on the handle grips, which causes the auger blade edges to frictionally engage the ground and pull the machine forward. The operator may also have to pull back slightly on the handle grips to control the speed at which the machine is propelled by the high-speed auger, which also discharges snow received into the intake of the machine through a discharge chute. The auger is selectively engaged by tensioning a belt which is reeved over pulleys attached to the auger and the output shaft of the engine.

[0003] Single-stage snow throwers are normally provided with a pair of rear wheels which are attached to the frame of the snow thrower and freely rotate in the forward and reverse directions; the snow thrower is supported by these wheels and may be manually pulled backward or pushed forward by the operator.

[0004] Compared to most single-stage snow throwers, even smaller dual-stage snow throwers are more complex and, consequently, more expensive. In addition to a rotating auger within the machine's snow intake, these machines include a high-speed, rotating impeller for discharging this snow through the discharge chute.

[0005] The rotating augers of dual-stage machines are not used for propulsion, and rotate relatively much slower than the augers of single-stage machines, which must also discharge the snow through the discharge chute. Dual-stage snow throwers are self-propelled through ground-engaging wheels, which are linked to the engine through a transmission means of any suitable type. The engines of such machines are generally located directly above the ground-engaging wheels; the engine weight and location provides dual-stage snow throwers with superior traction vis-a-vis single-stage machines.

[0006] Common types of dual-stage snow thrower transmissions include friction disk, gear shift, and hydrostatic, all of which are well known in the art. Providing even the least expensive of these transmission types adds considerably to the cost of a dual-stage snow thrower vis-a-vis a comparably-sized single-stage snow thrower.

[0007] Although both of the above-discussed means for self-propelling a snow thrower are preferable to pushing it manually, cost considerations aside, propelling it by powered ground-engaging wheels, rather than by the rotating auger, is generally preferable. Snow throwers having driven wheels track straighter, and do not wander to the left and right, as auger-driven snow throwers tend to do; thus, control of a wheel-propelled machine is usually easier. Further, as noted above, auger-driven snow throwers require the operator to lift up on the grips of the handle to bring the auger into engagement with the snow-covered surface; the weight of the machine, and its distribution, may be such that achieving good traction is difficult, particularly in deeper snow. Further, lifting the grips for prolonged periods may be ergonomically undesirable for the operator.

[0008] A single-stage snow thrower which may be inexpensively propelled by ground-engaging wheels would thus be desirable.

SUMMARY OF THE INVENTION

[0009] The present invention provides an inexpensive, single-stage snow thrower which is propelled by ground-engaging wheels, allowing it to track straighter and be better controlled than auger-propelled machines. The operator is also relieved of the burden of lifting the handle grips to achieve adequate traction; good traction is afforded by the engine being generally located above the driving wheels. Further, it is anticipated that the cost of the inventive snow thrower would be comparable to previous single-stage machines, and substantially less than a dual-stage snow thrower of comparable size.

[0010] The present invention provides a snow thrower including a frame, an engine attached to the frame and having a horizontal output shaft, the output shaft having a first axis of rotation, a first rotary member rotatably fixed to the engine output shaft, a rotating auger connected to the frame, the auger having a second axis of rotation, and a second rotary member rotatably fixed to the auger, the first and second rotary members being in selective operative engagement with each other, whereby the auger is selectively driven by the engine. An axle is connected to the frame and has a third axis of rotation, the first, second and third axes of rotation being substantially parallel. A third rotary member is in operative engagement with the axle, and a pair of ground-engaging wheels is attached to the axle. A fourth rotary member is rotatably fixed to the auger or the engine output shaft, and the third and fourth rotary members are in operative engagement with each other, whereby the axle is driven by the fourth rotary member.

[0011] The present invention also provides a snow thrower having a frame, an engine attached to the frame and having a horizontal output shaft, the output shaft having a first axis of rotation, a first rotary member rotatably fixed to the engine output shaft, and a rotating auger connected to the frame, the auger having a second axis of rotation. A second rotary member is rotatably fixed to the auger, the first and second rotary members forming a first pair of rotary members and being in selective operative engagement with each other, whereby the auger is selectively driven by the engine. An axle is connected to the frame and has a third axis of rotation, the first, second and third axes of rotation being substantially parallel. A third rotary member in is operative engagement with the axle, and a pair of ground-engaging wheels is attached to the axle. A fourth rotary member is rotatably fixed to either the auger or the engine output shaft, the third and fourth rotary members forming a second pair of rotary members and being in operative engagement with each other, whereby the axle is driven by the fourth rotary member. A belt is also included, at least one of the first and second pairs of rotary members being in operative engagement through the belt.

[0012] The present invention further provides a snow thrower having a frame, a snow inlet, a snow discharge chute and an engine connected to the frame, the engine having a horizontal output shaft, the output shaft having a first axis of rotation. A rotating, snow-collecting auger is connected to the frame and located between the snow inlet and the snow discharge chute, snow received into the snow inlet being forced by the auger through the snow discharge chute, the auger having a second axis of rotation. An axle is connected to the frame and has a third axis of rotation, the first, second and third axes of rotation being substantially parallel. A third rotary member is in operative engagement with the axle, to which a pair of ground-engaging wheels is attached, the snow thrower being self-propelled forwardly solely by the wheels. Also provided are means for selectively operatively engaging the auger and the axle to the engine output shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0014]FIG. 1 is a rear oblique view of a first embodiment snow thrower according to the present invention;

[0015]FIG. 2 is a side view of the snow thrower of FIG. 1;

[0016]FIG. 3 is a rear view of the snow thrower of FIG. 1;

[0017]FIG. 4 is an enlarged, fragmentary rear view of the snow thrower shown in FIG. 3;

[0018]FIG. 5 is a front oblique view of a second embodiment of a snow thrower according to the present invention;

[0019]FIG. 6 is rear oblique view of the snow thrower of FIG. 5;

[0020]FIG. 7 is a side view of the snow thrower of FIG. 5;

[0021]FIG. 8 is a side view of a third embodiment of a snow thrower according to the present invention;

[0022]FIG. 9 is a rear oblique view of a fourth embodiment of a snow thrower according to the present invention;

[0023]FIG. 10 is a side view of the snow thrower of FIG. 9; and

[0024]FIG. 11 is an enlarged, fragmentary rear view of the snow thrower of FIG. 9, its transaxle shown in section.

[0025] Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present invention. The exemplifications set out herein illustrate particular embodiments of the invention and are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

[0026] FIGS. 1-5 illustrate a first embodiment of a snow thrower according to the present invention. Snow thrower 20 a comprises engine 22 attached to body or frame 24. Body or frame 24 includes snow inlet 26 into which snow to be removed is received, and discharge chute 27 through which the removed snow is discharged by auger 28, which is located between snow inlet 26 and discharge chute 27. Auger 28 includes rotating blade 30 rotatably fixed to rotating shaft 32. Shaft 32 is supported at its opposite ends by means of bearings (not shown) attached to frame 24. Also attached to frame 24, at a location beneath engine 22, is axle 34 which is supported relative to frame 24 by means of bearings 36. Rotatably fixed to the opposite ends of axle 34 are ground-engaging drive wheels 38 and 40.

[0027] Engine 22 has horizontal output shaft 42, and the axes of rotation of auger shaft 32, axle 34 and engine output shaft 42 are all substantially parallel. First rotary member or pulley 44 is rotatably fixed to engine output shaft 42, and second rotary member or pulley 46 is rotatably fixed to auger shaft 32, the first and second pulleys forming a first pair of rotary members. Auger 28 is selectively operatively engaged to engine 22 through first belt 48 which is reeved about first pulley 44 and second pulley 46. First belt tensioner 50, which comprises a pulley rotatably attached to an elongate arm pivotally attached to frame 24, moves between a disengaged position and an engaged position. In its engaged position, first tensioner 50 engages the back side of first belt 48 and places the belt in a substantially tensioned state wherein first pulley 44 and second pulley 46 are operatively engaged through first belt 48, and power may be transferred from first pulley 44 to second pulley 46 for driving auger 28. Engine output shaft 42 rotates at approximately 3,600 rpm, and first pulley 44 and second pulley 46 are appropriately sized to result in auger 28 rotating at approximately 1,800 rpm. That is, first pulley 44 is approximately one-half the diameter of second pulley 46.

[0028] In the disengaged position of first belt tensioner 50, first belt 48 is in a substantially slackened state wherein first pulley 44 and second pulley 46 are out of operative engagement, and power is not transferred from first pulley 44 to second pulley 46. First belt tensioner 50 is biased through tension spring 52 into its disengaged position. Tension spring 52 has one end attached to the pivoting arm of first belt tensioner 50 and an opposite end attached to frame 24, and tends to pull first belt tensioner 50 into its disengaged position. First belt tensioner 50 is pulled into its engaged position, against the force of spring 52, by tensioning Bowden cable 54. Bowden cable 54 is connected to pivoting bail 56, which is attached to handle 58. Handle 58 is attached to frame 24 for providing an interface between an operator and snow thrower 20 a. Bowden cable 54 is coupled to first belt tensioner 50 and bail 56 in any suitable, well-known manner.

[0029] Third rotary member or pulley 60 a is rotatably fixed to axle 34 at a location intermediate ground engaging wheels 38 and 40. In snow thrower 20 a, fourth rotary member or pulley 62 a is rotatably fixed to engine output shaft 42, the third and fourth pulleys forming a second pair of rotary members. Second belt 64 is reeved about third pulley 60 a and fourth pulley 62 a. Second belt tensioner 66, which comprises a pulley rotatably attached to an elongate arm pivotally attached to frame 24, has an engaged position and a disengaged position. In its engaged position, second belt tensioner 66 engages second belt 64 and places the belt in a substantially tensioned state wherein third rotary member 60 a and fourth rotary member 62 a are in operative engagement through second belt 64, and power may be transferred therebetween for driving axle 34. Axle 34 is driven at approximately 400 rpm, and third pulley 60 a and fourth pulley 62 a are appropriately sized relative to each other to achieve the speed reduction from 3,600 rpm to 400 rpm.

[0030] In the disengaged position of second belt tensioner 66, second belt 64 is in a substantially slackened state wherein third rotary member 60 a and fourth rotary member 62 a are out of operative engagement, and power is not transferred therebetween. Second belt tensioner 66 is biased through tension spring 68 into its disengaged state. Tension spring 68 has one end attached to the pivoting arm of second belt tensioner 66 and an opposite end attached to frame 24, and tends to pull second belt tensioner 66 into its disengaged position. Second belt tensioner 66 is pulled into its engaged position, against the force of spring 68, by tensioning Bowden cable 70. Bowden cable 70 is connected to pivoting bail 72, which is also attached to handle 58. Bowden cable 70 is coupled to second belt tensioner 66 and bail 72 in any suitable, well-known manner.

[0031]FIGS. 6 and 7 illustrate a second embodiment of a snow thrower according to the present invention. Except as described below or shown in the drawings, second embodiment snow thrower 20 b is substantially identical in structure and function to first embodiment snow thrower 20 a. In snow thrower 20 b, fourth rotary member or pulley 62 a is rotatably fixed to auger shaft 32. Third rotary member or pulley 60 a is rotatably fixed to axle 34, and second belt 64 is reeved about these third and fourth pulleys.

[0032] Second belt tensioner 66 is pivotally attached to frame 24 and is biased into its disengaged position by spring 68. Second belt tensioner 66 is pulled against the force of spring 68 into its engaged position by tensioning Bowden cable 70, which is coupled to the arm of second belt tensioner 66 and bail 72, as described above. In the engaged position of second belt tensioner 66, second belt 64 is in a substantially tensioned state in which power may be transferred from fourth pulley 62 a to third pulley 60 a; axle 34 is thus selectively operatively engaged with auger 28 through second belt 64. As noted above, auger 28 rotates at approximately 1,800 rpm, and axle 34 rotates at approximately 400 rpm; third pulley 60 a and fourth pulley 62 a are appropriately sized to achieve a speed reduction from 1,800 rpm to 400 rpm. Means are thus provided for successively reducing the speed between the engine output shaft and the axle through rotation of the auger.

[0033]FIG. 8 illustrates a third embodiment of a snow thrower according to the present invention. Except as described below, third embodiment snow thrower 20 c is substantially identical in structure and function to second embodiment snow thrower 20 b. In snow thrower 20 c, second belt tensioner 66 does not selectively engage axle 34 and auger 28. Rather, second belt tensioner 66 is non-selectively fixed into its engaged position wherein second belt 64 is maintained in a substantially tensioned state. Those of ordinary skill in the art will now recognize that when auger 28 and engine 22 are selectively operatively engaged by movement of first belt tensioner 50 into its engaged position, axle 34 will likewise be engaged; i.e., axle 34 and auger 28 are simultaneously driven by engine 22. Notably, snow thrower 20 c comprises Bowden cable 54 and bail 56 only; it does not include Bowden cable 70 and bail 72.

[0034] FIGS. 9-11 illustrate a fourth embodiment of a snow thrower according to the present invention. Except as described below fourth embodiment snow thrower 20 d is substantially identical in structure and function to first embodiment snow thrower 20 a. In order to achieve the desired speed reduction between engine output shaft 42 and axle 34 without relying solely on the diameters of the driving and driven rotary members such as pulleys, which may result in an axle-mounted, driven pulley which is so large as to undesirably encounter snow, rocks or debris which may result in damage to the pulley and/or belt, or belt slippage, snow thrower 20 d comprises inexpensive transaxle 74 having a gear train which provides a substantial amount of the speed reduction needed for achieving the proper ground speed of the machine.

[0035] Referring particularly to FIG. 11, transaxle 74 includes casing 76 which is rotatable about the third axis of rotation of axle 34, which extends therethrough and is supported by bearings 78. Casing 76 is formed of mated casing portions 80, 82 attached together by bolts 84. Input shaft 86, which has an axis of rotation substantially parallel to that of axle 34, extends through casing portion 80 and is supported on bearings 88. Third rotary member or rubber-edged friction wheel 60 b is rotatably fixed to an exposed end of input shaft 86. Fourth rotary member or friction wheel 62 b is rotatably fixed to engine output shaft 42, the two friction wheels forming the second pair of rotary members in the present embodiment. Transaxle input shaft 86 is thus operatively engaged with engine output shaft 42 when friction wheels 60 b and 62 b are brought into frictional engagement.

[0036] As best shown in FIG. 11, disposed within casing 76 are four substantially identical compound gears 90, 92, 94, 96, each having a first, large diameter toothed portion and a second, small diameter toothed portion. Gears 90, 92, 94 and 96 may be formed of sintered powdered metal. As described further hereinbelow, driving gear 90 and driven gear 96, which are respectively rotatably fixed to the transaxle input shaft and its axle, are in operative engagement through intermediate gears 92 and 94, whereby rotation of the input shaft imparts speed-reduced rotation of the axle.

[0037] Driving compound gear 90 is rotatably fixed to input shaft 86 via a Woodruff key, and its small diameter portion is enmeshed with the large diameter portion of first intermediate compound gear 92, which is rotatably disposed about axle 34. The small diameter portion of first intermediate compound gear 92 is enmeshed with the large diameter portion of second intermediate compound gear 94, which is rotatably disposed about input shaft 86. The small diameter portion of second intermediate compound gear 94 is enmeshed with the large diameter portion of driven compound gear 96, which is rotatably fixed to axle 34 via a Woodruff key. The first and second toothed portions of the compound gears may be sized to produce a speed reduction of 36:1 between input shaft 86 and axle 34. Third and fourth rotary members 60 b and 62 b, respectively, are also appropriately sized to achieve the desired axle speed of 400 rpm when driven by engine output shaft 42, which rotates at approximately 3,600 rpm. Notably, driving and driven gears 90 and 96, respectively, need not be compound gears; the large diameter portion of driving gear 90 and the small diameter portion of driven gear 96 are not enmeshed with another gear. Nevertheless, certain economies of scale may be realized by using four identical gears 90, 92, 94, 96 rather than three unique gear designs, i.e., a small diameter first, driving gear 90 rotatably fixed to input shaft 86; two identical intermediate compound gears 92, 94 respectively rotatably disposed about axle 34 and input shaft 86; and a large diameter fourth, driven gear 96 rotatably fixed to axle 34.

[0038] Referring to FIGS. 10 and 11, casing 76 is rotatable in opposite directions about the third axis of rotation, and is provided with at least one arm 98 to which tension spring 68 and Bowden cable 70 are attached. Arm(s) 98 may be integrally formed to one or both of the casing portions, or may be stamped from steel and bolted thereto. Casing portions 80, 82 are formed of substantially identical castings, with casing portion 80 being cast or machined to accommodate the passage of axle 34 therethrough. Thus, a casing 76 is provided which is substantially symmetrical about a plane 100 (FIG. 10) which extends through the axes of rotation of input shaft 86 and axle 34. Those of ordinary skill in the art will recognize that casing portions 80, 82 may be formed of identically-shaped metal stampings instead of being castings.

[0039] The force of tension spring 68 biases rotatable transaxle casing 76 into a disengaged position in which friction wheels 60 b and 62 b are separated and out of frictional engagement, and no power is transferred from engine 22 to transaxle 74. In this position, the axle is out of operative engagement with the engine output shaft, and the axle is not driven by the running engine. Manipulation of bail 72 draws cable 70 into a tensioned state against the force of spring 68 and rotates casing 76 about the third axis of rotation into an engaged position in which friction wheel 60 b is moved into frictional contact with friction wheel 62 b, and power may be transferred therebetween. In this position, the axle is in operative engagement with the engine output shaft, and axle 34 is driven by engine 22 through transaxle 74.

[0040] While this invention has been described as having exemplary designs, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains. 

What is claimed is:
 1. A snow thrower comprising: a frame; an engine attached to the frame and having a horizontal output shaft, said output shaft having a first axis of rotation; a first pulley rotatably fixed to said engine output shaft; a rotating auger connected to said frame, said auger having a second axis of rotation; a second pulley rotatably fixed to said auger; a first belt extending between said first and second pulleys, said auger in selective operative engagement with said engine output shaft through said first belt; an axle connected to said frame and having a third axis of rotation; a third pulley in operative engagement with said axle; a pair of ground-engaging wheels attached to said axle; a fourth pulley rotatably fixed to one of said auger and said engine output shaft; and a second belt extending between said third and fourth pulleys; and wherein said first, second and third axes of rotation are substantially parallel, and said axle is coupled to one of said auger and said engine output shaft through said second belt.
 2. The snow thrower of claim 1, wherein said third pulley is rotatably fixed to said axle.
 3. The snow thrower of claim 1, further comprising a belt tensioner attached to said frame, said belt tensioner having an engaged position in which said first belt is in a substantially tensioned state and said auger is in operative engagement with said engine output shaft, and a disengaged position in which said first belt is in a substantially slackened state and said auger is out of operative engagement with said engine output shaft.
 4. The snow thrower of claim 3, wherein said belt tensioner is biased into its said disengaged position.
 5. The snow thrower of claim 3, wherein said fourth pulley is rotatably fixed to said auger, and said axle is in selective operative engagement with said auger through said second belt.
 6. The snow thrower of claim 5, further comprising means for successively reducing the speed between said engine output shaft and said axle through rotation of said auger.
 7. The snow thrower of claim 5, wherein said belt tensioner is a first belt tensioner, and further comprising a second belt tensioner attached to said frame, said second belt tensioner having an engaged position in which said second belt is in a substantially tensioned state and said axle is in operative engagement with said auger, and a disengaged position in which said second belt is in a substantially slackened state and said axle is out of operative engagement with said auger.
 8. The snow thrower of claim 7, wherein said second belt tensioner is biased into its said disengaged position.
 9. The snow thrower of claim 3, wherein said fourth pulley is rotatably fixed to said auger, and said axle is in fixed operative engagement with said auger through said second belt.
 10. The snow thrower of claim 9, wherein said belt tensioner is a first belt tensioner, and further comprising a second belt tensioner attached to said frame, said second belt tensioner having a non-selective engaged position in which said second belt is in a substantially tensioned state and said axle is in fixed operative engagement with said auger.
 11. The snow thrower of claim 1, wherein said fourth pulley is rotatably fixed to said engine output shaft, and axle is in selective operative engagement with said engine output shaft through said second belt.
 12. The snow thrower of claim 11, further comprising: a first belt tensioner attached to said frame, said first belt tensioner having an engaged position in which said first belt is in a substantially tensioned state and said auger is in operative engagement with said engine output shaft, and a disengaged position in which said first belt is in a substantially slackened state and said auger is out of operative engagement with said engine output shaft; and a second belt tensioner attached to said frame, said second belt tensioner having an engaged position in which said second belt is in a substantially tensioned state and said axle is in operative engagement with said engine output shaft, and a disengaged position in which said second belt is in a substantially slackened state and said axle is out of operative engagement with said engine output shaft.
 13. The snow thrower of claim 12, wherein said first and second belt tensioners are each biased into their respective said disengaged positions.
 14. A snow thrower comprising: a frame; an engine attached to the frame and having a horizontal output shaft, said output shaft having a first axis of rotation; a first rotary member rotatably fixed to said engine output shaft; a rotating auger connected to said frame, said auger having a second axis of rotation; a second rotary member rotatably fixed to said auger, said first and second rotary members comprising a first pair of rotary members and being in selective operative engagement with each other, whereby said auger is selectively driven by said engine; an axle connected to said frame and having a third axis of rotation, said first, second and third axes of rotation being substantially parallel; a third rotary member in operative engagement with said axle; a pair of ground-engaging wheels attached to said axle; a fourth rotary member rotatably fixed to one of said auger and said engine output shaft, said third and fourth rotary members comprising a second pair of rotary members and being in operative engagement with each other, whereby said axle is driven by said fourth rotary member; and a belt, at least one of said first and second pairs of rotary members being in operative engagement through said belt.
 15. The snow thrower of claim 14, wherein said first pair of rotary members is in operative engagement through a first said belt, and said second pair of rotary members is in operative engagement through a second said belt.
 16. The snow thrower of claim 14, further comprising a transaxle, said transaxle comprising: a casing through which said axle extends; an input shaft to which said third rotary member is rotatably fixed, said input shaft extending into said casing; and speed reduction gearing disposed within said casing and through which said axle is driven by said transaxle input shaft.
 17. The snow thrower of claim 16, wherein said third and fourth rotary members each comprise a friction wheel, said friction wheels being in selective frictional engagement with each other, whereby power is selectively transferred from said engine output shaft to said transaxle input shaft.
 18. The snow thrower of claim 16, wherein said transaxle input shaft has an axis of rotation which is fixed relative to said transaxle casing and substantially parallel with said third axis of rotation.
 19. The snow thrower of claim 18, wherein said transaxle casing is rotatable about said third axis of rotation, said transaxle casing having an engaged position in which said third and fourth rotary members are in frictional engagement with each other, and a disengaged position in which said third and fourth rotary members are out of frictional engagement with each other.
 20. The snow thrower of claim 19, wherein said transaxle casing is biased into its said disengaged position.
 21. The snow thrower of claim 16, wherein said speed reduction gearing comprises a driving gear rotatably fixed to said transaxle input shaft and a driven gear rotatably fixed to said axle, said driving and driven gears being in engagement.
 22. The snow thrower of claim 21, wherein said driving and driven gears are in engagement through at least one intermediate gear disposed therebetween.
 23. The snow thrower of claim 21, wherein said speed reduction gearing further comprises a first intermediate gear rotatably disposed about said axle, and a second intermediate gear rotatably disposed about said transaxle input shaft, said first intermediate gear in meshed engagement with said driving gear and said second intermediate gear, said second intermediate gear in meshed engagement with said first intermediate gear and said driven gear.
 24. The snow thrower of claim 23, wherein at least two of said driving, first intermediate, second intermediate and driven gears are compound gears having first and second toothed portions of differing diameters.
 25. The snow thrower of claim 24, wherein said driving, first intermediate, second intermediate, and driven gears are all compound gears, each having first and second toothed portions of differing diameters.
 26. The snow thrower of claim 25, wherein said driving, first intermediate, second intermediate, and driven gears are substantially identical.
 27. The snow thrower of claim 16, wherein said casing is substantially symmetrical in shape about a plane extending through said transaxle input shaft and said axle.
 28. The snow thrower of claim 16, wherein said casing comprising first and second casing portions which are substantially identical in shape.
 29. The snow thrower of claim 28, wherein said casing portions are formed of substantially identical castings.
 30. A snow thrower comprising: a frame; a snow inlet connected to said frame; a snow discharge chute connected to said frame; an engine attached to the frame and having a horizontal output shaft, said output shaft having a first axis of rotation; a rotating, snow-collecting auger connected to said frame and located between said snow inlet and said snow discharge chute, snow received into said snow inlet being forced by said auger through said snow discharge chute, said auger having a second axis of rotation; an axle connected to said frame and having a third axis of rotation, said first, second and third axes of rotation being substantially parallel; a third rotary member in operative engagement with said axle; a pair of ground-engaging wheels attached to said axle, said snow thrower being self-propelled forwardly solely by said wheels; and means for selectively operatively engaging said auger and said axle to said engine output shaft. 